Second pilot trials of the STAR-Liege protocol for tight glycemic control in critically ill patients

Abstract

Background: Critically ill patients often present increased insulin resistance and stress-induced hyperglycemia. Tight glycemic control aims to reduce blood glucose (BG) levels and variability while ensuring safety from hypoglycemia. This paper presents the results of the second Belgian clinical trial using the customizable STAR framework in a target-to-range control approach. The main objective is reducing measurement frequency while maintaining performance and safety of the glycemic control.

Methods: The STAR-Liege 2 (SL2) protocol targeted the 100-140 mg/dL glycemic band and offered 2-hourly and 3-hourly interventions. Only insulin rates were adjusted, and nutrition inputs were left to the attending clinicians. This protocol restricted the forecasted risk of BG < 90 mg/dL to a 5% level using a stochastic model of insulin sensitivity to assess patient-specific responses to insulin and its future likely variability to optimize insulin interventions. The clinical trial was performed at the Centre Hospitalier Universitaire de Liege and included 9 patients. Results are compared to 24-hour pre-trial and 24-hour post-trial, but also to the results of the first pilot trial performed in Liege, STAR-Liege 1 (SL1). This trial was approved by the Ethics Committee of the Medical Faculty of the University of Liege (Liege, Belgium).

Results: During the SL2 trial, 91 measurements were taken over 194 hours. BG levels were tightly distributed: 54.9% of BG within 100-140 mg/dL, 40.7% were ≥ 140 mg/dL and 4.4% were < 100 mg/dL with no BG < 70 mg/dL. Comparing these results with 24-hour pre-trial and post-trial shows that SL2 reduced high and low BG levels and reduced glycemic variability. Nurses selected 3-hourly measurement only 5 of 16 times and overrode 12% of 91 recommended interventions (35% increased insulin rates and 65% decreased insulin rates). SL1 and SL2 present similar BG levels distribution (p > 0.05) with significantly reduced measurement frequency for SL2 (p < 0.05).

Conclusions: The SL2 protocol succeeded in reducing clinical workload while maintaining safety and effectiveness of the glycemic control. SL2 was also shown to be safer and tighter than hospital control. Overall results validate the efficacy of significantly customizing the STAR framework.

Figure 1

Steps of the STAR-Liege 2 protocol.

Figure 2

Overlapping of glycemic target band (green) and stochastic predicted range (blue) with BG_5th≥ 90 mg/dL.

Figure 3

Clinical process during glycemic control.

Figure 4

Whole cohort cumulative density function (CDF) for BG (left panel), insulin rates (middle panel) and exogenous glucose rate (right panel). Results of the STAR-Liege 1 (SL1, green) and STAR-Liege 2 (SL2, blue) clinical trials are illustrated.

Figure 5

Cumulative density function (CDF) for BG levels for 24-hour pre-trial, during trial and post-trial for SL2 pilot trial. Target band bounds (100 mg/dL and 140 mg/dL) are highlighted.